How to download Excel template file from folder attachment using angul

Question

I work on project angular 7 and web API asp.net core 2.2 I face issue I can't get Template Excel file

 

Exist on Server found on folder Attachment and file Name Delivery.xlsx to download it .

 

I only Need When click on download Button download Template Excel file from folder attachment

 

my issue How to get file Delivery.xlsx from attachment Folder and assign it on angular 7 to download ?

 

component.html

<input type="button" class="btn btn-success" value="Download" (click)="download()" style="margin: 20px 0;"/>

component.ts

download(file) {

    let fileName = ???;
    let checkFileType = fileName.split('.').pop();
    var fileType;

    if (checkFileType == ".xlsx") {
        fileType = "application/vnd.openxmlformats officedocument.spreadsheetml.sheet";
    }

    this.DownloadFile(fileName, fileType)
        .subscribe(
            success => {
                saveAs(success, fileName);
            },
            err => {
                alert("Server error while downloading file.");
            }
        );
}

DownloadFile(filePath: string, fileType: string): Observable<any> {

    let fileExtension = fileType;
    let input = filePath;

    return this.http.get('https://localhost:44396/api/ApprovalQuality/download'+ "?fileName=" + input, {

        responseType: 'blob',
        observe: 'response'
    })
        .pipe(
            map((res: any) => {
                return new Blob([res.body], { type: fileExtension });
            })
        );
}

Web API .net core 2.2

[HttpGet]
[Route("Download")]
public IActionResult Download()
{
    string filename = null;
    if (filename == null)
        return Content("filename not present");

    var path = Path.Combine(
                   Directory.GetCurrentDirectory(),
                   "Attachment", filename);

    var memory = new MemoryStream();
    using (var stream = new FileStream(path, FileMode.Open))
    {
         stream.CopyTo(memory);
    }
    memory.Position = 0;
    ExcelEx ex = new ExcelEx();
    return File(memory, ex.GetContentType(path), Path.GetFileName(path));
}